*Por favor corregirme mis errores.*
En mi libro de español escritura se dice: "Elige una de las frases o palabras para terminar las oraciones"
¿Por qué no omite "para"? ¿Qué es el uso?
A veces veo a "para" usado al lado de verbo.

See a translation

'Por favor corregirme mis errores' that's ok, and I can understand what you mean, but it sounds just a bit unnatural. I would use: 'Por favor corrijan mis errores'

corrijan = correct (as in '(you -plural-) correct my mistakes)

'En mi libro de español escritura se dice'

You mean 'spanish writing book'? I think you can add another 'de' so it says that your book is about spanish, and also that your spanish book is a writing book: libro de español de escritura'.

Instead of 'se dice' you can only say 'dice'. Because your book says (...). We use 'se dice' more like 'they say', as in a rumor or popular knowledge. Ex. They say you can use ginger to aliviate pain. Dicen/Se dice que puedes usar gengibre para aliviar el dolor.

'¿Qué es el uso?' - ¿Cuál? would fit this question better. You could also ask 'how is this used' '¿cómo se usa?'

You're doing and overall great job communicating! 😭💜 Felicidades! Haces un gran trabajo comunicandote!! 👏👏👏

And para in this context is used between what you're doing (elegir una frase) and why you're doing it (para terminar las oraciones).

When you see 'para' between two actions like this it usually has to answer the question why?

Como (I eat)

Why? (¿Por/para qué?)

Para nutrirme. (To nourish my self)

Como para nutrirme. (I eat to nourish myself.)

Saludos y suerte con tus estudios! 😊👋💪